Greetings,
I am attempting to use the Mad library to decode 32kbps/22khz streams. I'm having difficulty however with the output being too fast (e.g. it seems about twice as fast). I'm not sure if this is related to the library at all - but I can't seem to find a definitive answer as to if this library supports lower sample rates. From glancing through the code it appears to, but I have also seen a couple of posts elsewhere that state that libmad does not support 22khz streams.
Can someone please confirm this one way or another for me?
Thanks,
-Matt
On Aug 20, 2006, at 9:58 PM, Matthew Twomey wrote:
I am attempting to use the Mad library to decode 32kbps/22khz streams. I'm having difficulty however with the output being too fast (e.g. it seems about twice as fast). I'm not sure if this is related to the library at all - but I can't seem to find a definitive answer as to if this library supports lower sample rates. From glancing through the code it appears to, but I have also seen a couple of posts elsewhere that state that libmad does not support 22khz streams.
Can someone please confirm this one way or another for me?
You should not have trouble decoding 32 kbps or 22050 Hz streams.
You should check that you are properly handling the output. For example, if the stream is single channel (mono) but you are playing it as if it were stereo, it will sound twice as fast. The same effect could also happen, for example, if your hardware doesn't support a 22050 Hz sampling frequency and will only play at 44100 Hz. In that case you would need to resample the output before passing it to your audio driver or DAC.
Rob - thank you, that is what I suspected.
I'm new to this (mp3 decoding and PCM in general) so I'm still finding my way. I'm working on an audio book player for the Sony PSP (which is why I'm using the lower sample/bit rates).
I'll look more closely at what I'm doing with the output.
Thanks,
-Matt
-----Original Message----- From: mad-dev-bounces@lists.mars.org [mailto:mad-dev- bounces@lists.mars.org] On Behalf Of Rob Leslie Sent: Monday, August 21, 2006 12:31 AM To: mad-dev@lists.mars.org Subject: Re: [mad-dev] Question regarding library cababilities (32kbps/22khz)
On Aug 20, 2006, at 9:58 PM, Matthew Twomey wrote:
I am attempting to use the Mad library to decode 32kbps/22khz streams. I'm having difficulty however with the output being too fast (e.g. it seems about twice as fast). I'm not sure if this is related to the library at all - but I can't seem to find a definitive answer as to if this library supports lower sample rates. From glancing through the code it appears to, but I have also seen a couple of posts elsewhere that state that libmad does not support 22khz streams.
Can someone please confirm this one way or another for me?
You should not have trouble decoding 32 kbps or 22050 Hz streams.
You should check that you are properly handling the output. For example, if the stream is single channel (mono) but you are playing it as if it were stereo, it will sound twice as fast. The same effect could also happen, for example, if your hardware doesn't support a 22050 Hz sampling frequency and will only play at 44100 Hz. In that case you would need to resample the output before passing it to your audio driver or DAC.
-- Rob Leslie rob@mars.org
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Matthew Twomey -
Rob Leslie